This fallacious idea needs to die.
I was around in the long long ago, when the voting system actually meant something. People with unpopular opinions might have seen a few downvotes thrown their way, but no one was ever negbombed or silenced for having an unpopular opinion, and they aren't now either.
The occasions when posters with a dissenting opinion get negbombed are as follows:
*When they're being dicks about their unpopular opinion.
*When they whine about the "hive mind" being against them.
*When they whine about MGoPoints.
*When they exhibit a martyr complex with regard to their opinion ("I know I'm going to be negged for this, but it needs to be said..." "I'm going to educate all of you fools who just don't want to accept the TRUTH!" Dahblue is a prime example of a poster who continuously does this.).
So it basically comes down to "don't be a dick" or self important, and you'll do just fine. People are more than willing to upvote unpopular or dissenting opinions, especially when they are well thought out and/or have some sort of statistical backing.
The problem is when people with obvious/stupid/whiny/bitchy opinions think that they're being victimized by downvotes because their posts go against the hive mind, when in reality, they're being downvoted because they have obvious/stupid/whiny/bitchy opinions. 99% of negbombings based on the poster having an unpopular opinion fall into this category.